Projekt

Havixbeck – a city with solar potential

1) Purpose of the project

The discussion about the reduction of CO2 is of increasing importance in different social contexts. International negotiations about targets for the reduction of CO2 are widely covered by the media. These negotiations are closely connected to the problems of climate change and energy resources for the future. It is the purpose of the project to produce a solar land register for the city of Havixbeck. This is done to

• find out to what extent solar energy can contribute energy for the city of Havixbeck and
• to provide a guideline for the residents of Havixbeck who are thinking about using solar energy

2) History of the project

When they were still in grade 11 students of Anne-Frank-Gesamtschule started dealing with solar energy in Havixbeck. They conducted a survey in two residential areas of Havixbeck in order to raise an inventory of solar plants.
This project was encouraged and conducted with the help of the local building authorities. In co -operation with the University of Münster, Institut für Geoinformatik, the current project was subsequently developed as a continuation. Its purpose is to look closer into the use of solar energy.

3) Description of the project 'Solarvixbeck'

In the course of a ‘project week’ 12th grade students of Anne-Frank-Gesamtschule deal with the solar potential of houses in Havixbeck. The purpose of the project of Anne-Frank-Gesamtschule and the “Institut für Geoinformatik” is to offer residents of Havixbeck the possibility to find out the solar potential of their house. This should provide house owners with a possible guideline for acquiring a solar plant. The solar potential of a house may be determined by the following criteria:

• 1. Pitch of the roof (ideally 30°)
• 2. Exposition of the house (preferably southward looking)
• 3. Utilisable space (min. 20 m²)
• 4. Possible shadows (e.g. high trees or buildings)

Before they started the students were informed about the way solar collectors work and what different kinds of solar collectors there are when they visited ‘SK-solar’, a local enterprise. To measure the pitch of a roof students built sextants. When they were out in the streets measuring they took down notes about possible shadows on the roof.
The exposition of the house and the usable space for solar collectors was calculated later with the help of a special software (ESRI/ARCGIS) in the computer-rooms of Anne-Frank-Gesamtschule. Students of the ‚Institut für Geoinformatik der WWU‘ and staffs helped preparing and conducting the project.

The State Survey Office NRW kindly provided us with data and plans of the buildings. The data were then linked with satellite pictures and a survey map (1 : 5000) in ArcGIS . screenshot. The size of the usable space on the roof was calculated by means of satellite pictures and the pitch of the roof :

usable area for solar energy = (roofl area of the sattelite picture)/(2 *〖 cos〗⁡〖 (roof angle〗))

Further important aspects which had to be taken into account were : the form oft he roof and the presence or absence of balconies.

• With a pavilion roof you can use no more than about 50% oft he space. Foto
• On a hip roof 25% oft he usable space has to be deducted. Foto

Furthermore there are different kinds of solar panels which ask for different requirements as far as the pitch of the roof, shadow and usable space are concerned:

• Solar modules based on crystalline structures provide a higher degree of efficiency and require only a smaller space.
• Thin-layer modules make better use of diffuse light and are easier to handle. But their efficiency is inferior as a rule and they require a larger space.

In the end all the date were fed into ARCGIS to determine the solar potential of each building.